The present invention relates to contact image sensors for fax machines and scanners, and relates more particularly to such a contact image sensor which eliminates the floating of the image signal detected.
A regular contact image sensor for use in a fax machine or scanner is shown in FIG. 1. This structure of contact image sensor is comprised of a driver (1'), a first sensor chip (2'), a second sensor chip (3'), an analog switch (4'), a capacitor (5'), an operational amplifier (6'), and a power supply (7'). The power supply (7') provides +5V and -12V DC to the other parts of the contact image sensor. This structure of contact image sensor is complicated and expensive. Furthermore, it requires much installation space.